1. Field of the Invention
The present invention relates to a fuel injector (injection valve) and a nozzle body thereof, and also to a method of manufacturing a cylindrical part equipped with a fluid passage, such as a nozzle body.
2. Prior Art
Since the nozzle body of a fuel injector has been required to have corrosion resistance and abrasion resistance, martenstic (martensite) stainless steel has been used as the material meeting the requirement.
A conventional nozzle body made of martenstic stainless steel has been manufactured by cutting or forging.
The Japanese Application Patent Laid-Open Publication No. Hei 5-164016 proposes to manufacture some parts constituting a fuel injector (a case supporting a valve assembly, and a part supporting a coil assembly) by drawing, but nozzle body is not included.
Other cylindrical part than a fuel injector, in which a fluid passage is formed, has never been manufactured by drawing martentic stainless steel.
A method employed for manufacturing a cylindrical part from martenstic stainless steel has been such that the part is cut from a bar or forged from a coil sheet into a rough shape and then finished by grinding. There has been a method of manufacturing a cylindrical part from a steel plate by drawing but, in the case of using martenstic stainless steel, this has never been applied to mass-production.